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The skinny on trans fats

By JANET K. KEELER
Published December 7, 2006


This week's ban on trans fats in New York City restaurants is another move to rid our diets of what some health officials call the most unhealthy fat in America.

As of Jan. 1, all foods sold in grocery stores were required to include trans fat content in their nutritional labeling. As a result, you see colorful notes on the front of some crackers, cookies and cereals proudly proclaiming their zero trans fat status.

Wendy's has mostly booted the artery-clogging fat from its fryers, though it took the chain two years to find a suitable substitute. Taco Bell and Kentucky Fried Chicken will change over in April. McDonald's, which is trans-fat-free in Denmark by law, has not made the switch but will have to by July to comply with the New York law.

But just what is trans fat, and why are health experts so down on it?

What are trans fats?

Trans fats, a shortened term for trans fatty acids, are liquid vegetable fats made solid by adding hydrogen to the oil, such as in some vegetable shortenings and hard margarines. If the substance stays solid at room temperature, it's probably trans fat. They are sometimes called artificial fat.

What is their purpose?

Trans fats, popularized by Crisco a century ago, are used mostly in commercial baked goods and for frying food. Less expensive than animal fats like butter and lard, these fats last longer than other vegetable oils. They contribute to the texture of food and increase the shelf life of baked goods, which is why you are more likely to find them in a packaged snack cake at the quickie mart than in a cake freshly baked at a bakery.

Crisco makes a shortening with zero trans fats now, though you can still buy the original. Given the intense bad publicity against trans fats, food scientists, manufacturers and restaurants are moving quickly to find substitutes.

The hydrogenated oil used in fast food frying stays stable longer than pure vegetable oil, which allows the restaurant to use it repeatedly. Oils such as canola, olive and corn go rancid more quickly.

Is there a taste difference?

Yes, and that's why fast food chains have been so reluctant to change, especially when it comes to french fries. In crackers and cookies, there might be less snap without trans fat.

Why are trans fats so bad?

Research shows that trans fats not only increase bad cholesterol (LDL), they also scrub away good cholesterol (HDL). So they represent a double-whammy for hardening of the arteries and heart disease. Nutritional experts are concerned especially about the effect on children.

Skeptics about a trans fat threat say that we've been eating trans fats for 100 years and are living longer. Plus, there is some debate about what's worse for our diets: fat or carbohydrates.

Do trans fats have more calories?

No, hydrogenating an oil does not significantly change its calorie or fat content.

All oils have about 120 calories and 14 grams of fat per tablespoon.

A study released by Harvard Medical School in October reported that people who eat a lot of food with trans fat gain more weight than people who consume equivalent calories in healthier fats.

Experts have long thought there is an association between weight gain and trans fat, but research is inconclusive about why.

What should I look for on labels?

In addition to checking the nutrition labels for trans fat content, look on the ingredients list for the words "hydrogenated" or "partially hydrogenated" attached to canola, soybean or cottonseed oil. Those are trans fats.

Do I use trans fats in my kitchen?

Even if you don't cook with solid margarine or shortening, you'll certainly find trans fats in groceries. Read the labels on such common foods as microwave popcorn, baking mixes, canned icing, canned soup and dry soup mix, toaster pastries, refrigerated biscuits and cookie dough, muffins, cookies and crackers.

Janet K. Keeler can be reached at (727) 893-8586 or jkeeler@sptimes.com.

Sources: U.S News & World Report, Associated Press, American Heart Association, New York Times, Business Week, University of Maryland.